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Why are cockpit voice recorders limited to 2 hours recording?
With today's technology in memory storage, where simple voice recorders can record virtually endless durations, why are CVRs limited to only 2 hours. Is it the eternal "cost vs benefit" reason?
Wouldn't more recording provide greater insight to investigators in case of any disaster?

Conversation and cockpit noises prior to two hours before an accident are deemed not useful to help explain the accident, but they can contain privacy elements? Technical parameters recording is longer.

Lets see. 44.1 kHz * 2 B/channel * 5 channels * 2 h ~ 3 GiB. This is not compressed, but I think it indeed isn't, because compression would be another thing that might fail and it would render much more of the recording unreadable if there was minor damage to the chip. They may not be using as good quality, but on the other hand they may actually duplicate the recording. Add the age of the units, as it took some time to develop, certify and deploy them and the desire to use lower density chips that are more robust and it no longer sounds too easy to keep 2 hours.

Also, the “quick access recorder” usually keeps a lot more. But it does not have any of the reliability and durability requirements; it is intended for internal reviews after flight and possibly investigating incidents (= when something went wrong, but no serious injury or significant damage occurred).

Planes that fly today weren't built today, they were built yesterday, which means that today's technology didn't exist when they were built. By the way: did you try blowing up your simple voice recorder, then dropping it 30000 feet, then submerging it in aggressive salt water for 6 months, then plug it in and play it back? Did it work?

@JörgWMittag So you are trying to tell me that the current technology is not advanced enough to accommodate more than 2hours of great quality recording in the bullet proof CVRs?

@mins I'm just trying to understand this 2 hour rule, do you have some more on that. Common sense implies the more data the better, atleast for the entire duration of the flight.

A lot of pilots have privacy concerns with the CVRs already, I am sure ultimately the two hour limit is a balance point between investigation and privacy. This is the same reason the crew can clear the CVR after a flight. I work with a guy that listened to a full CVR after an accident that included the previous flight, on that previous flight the pilots were bashing their families hardcore and talking about sleeping around, not the kind of thing you want out in world after you die.

@Firee:  What do you imagine could have happened more than 2 hours ago that leads to an incident.   In virtually all cases, the time between "everything is normal" to "Sound of Impact" is less than 10 minutes.  Even flight Quantas 32 (one of the longest emergencies in history) was only 1:45 from engine failure to landing.   One rare exception is Payne Stewart's crash (roughly 3:30 from depressurization to crash).

@OSUZorba already explained the balance between privacy and investigation needs. Pilots (like everybody should) have a right to discuss in privacy. When you are at work (and they are) not everything you say is for work purpose, you need to relax, that's part of the well being required to work safely. If everything were recorded, everybody would be stressed, that's not what you want as a passenger. Regarding the state of technology, I agree with you that we could today record ten 6 kHz channels, for 20 hours if we needed it, only slow static memory is needed, not fast DDR.

@abelenky I can imagine these: MH370, 2014 TBM-900 crash, and Helios 522 off the top of my head. Also, QF32, though it didn't crash and the pilots could be interviewed. Sometimes things which happened much earlier in flight can end up causing problems later (Space Shuttle Columbia is an extreme example of this.)

I specifically cited QF32 as being under 2 hours from incident to landing.  We still don't have the location of the boxes from MH370, so 2 hours or 1,000 hours of recording time doesn't matter.  The other two are pressurization / hypoxia incidents which are well understood and additional recording time would not shed any new light.   I think you proved my point.  Thank you.

@abelenky Ah, so you did. Somehow I missed that sentence. However, I'm not sure when the CVR stopped on that flight, since they weren't able to shut down the #1 engine until 3 hours after landing. If the CVR didn't stop until the #1 engine was shut down (or after,) they'd have erased the entire relevant portion of the incident, other than the fight to shut down #1. With MH370, we don't have it yet, but hopefully we eventually will. However, we'll almost certainly not have the most important part of the flight recorded, due to the 2 hour limit.

Respecting pilot's privacy, the CVR recording can be deleted by the pilot at the end of the flight. In case there is an accident, I personally feel, safety would precede privacy. More information would indeed assist the investigators. Plus I'm sure, laws can be made to safeguard pilot's private conversations.

@reirab Exactly. Having more data, would always give a better insight.I'm yet to be convinced cost and technology are big hindrance to adopting this initiative. Pilot privacy is one valid point, but since pilots have the option of erasing the recording after landing, solves the issue of longer recordings. Ideally, the recording length should be from the moment pilots start operating in the cockpit.

@vasin1987 Why am i not able to see your comment? Instead I see a big white space.

@Firee must be some formatting issue. I can see my comment well in SE android app but big white space on iOS safari. I put a lot of dollar sign there. Basically it comes down to cost vs benefit arguement again.

@Firee you probably exceeded the 2-hour limit to read the comment, and it was erased.

@vasin1987 I cannot see your comment either. Dollar signs are a code-element of javascript, so it's possible that the server is interpreting it as script code to be executed. If so, you may have inadvertently discovered an injection vulnerability (hacking). Hopefully the admins will look at this soon.

@DrZ214 Hogwash, $ signs are no more javscript code than xyz. It is a client side library called Mathjax which allows you to style math formulas in a nice way, just put LaTeX like stuff in paired dollar signs, and the library will try to render it. It appears an empty math expression turned into an empty block which is unfortunate. As an example $\sqrt{A^3}$ turns into $\sqrt{A^3}$

Its strange actually. In chrome on desktop, I see a big white space, the space is disproportionately bigger than the number of dollar characters. However, I can see the dollar characters in the Stackexchange android app.

@falstro sorry, maybe it was the question marks that delimited javascript code? Today we use <script>. But dollar signs are still used in it, such as this example: http://stackoverflow.com/questions/10607847/how-does-inline-javascript-in-html-work . @Firee Mobile browsers such as safari render html significantly differently than desktop browsers such as chrome. On top of that, many websites serve different page layouts depending on if it detects a mobile or desktop device. Pretty sure all SE pages do that. Usually you can tell when it's something like m.stackexchange.com.

@DrZ214 this isn't the correct forum, but '$' in javascript is just a letter, alone it's commonly the function name for the jQuery library (but other libraries have adopted the same idea), so when you see $(...) it's calling the $ function with ... parameters. There never was anything but '
Aviation manufacturers generally design the equipment to comply with legal requirements. Under FAA two hours is what is required by law.

14 CFR  121.359–Operating Requirements:  Domestic,  Flag,  and Supplemental  Operations–Cockpit  Voice  Recorders
(i)  By  April  7,  2012, all  turbine  engine-powered  airplanes  subject to  this  section  that are manufactured  before  April  7, 2010, must  have  a  cockpit  voice  recorder  installed that  also—
(1)  Meets  the  requirements  of  §23.1457(d)(6)  or  §25.1457(d)(6)  of  this  chapter, as  applicable;
(2)  Retains  at  least  the  last  2 hours  of  recorded  information using  a  recorder  that  meets  the standards  of  TSO-C123a,  or  later  revision;  and
(3)  Is  operated  continuously  from  the  use  of  the  checklist  before  the  flight  to completion of  the final checklist at the  end  of  the  flight.
(4)  If  transport  category,  meets  the  requirements  in §25.1457(a)(3),  (a)(4),  and  (a)(5) of this chapter.
[The following section has the same requirements for aircraft manufactured after April 7, 2010.]

The flight data recorder is required to retain 15 hours worth of data.
FAA allows pilots to erase anything on the CVR recorded 30 min (in some cases 15 min) prior. This is probably something that was negotiated between the NTSB and the pilots union to protect the pilots' privacy.  Since it's written into the statute that way I assume modern digital CVR'S must have a function to erase everything but the last 30 min. (@OSUZorba there's that word again)

14 CFR  121.359 (f)  In  complying  with this  section, an approved  cockpit  voice  recorder  having  an  erasure feature  may  be  used, so that  at  any  time  during  the  operation of  the  recorder, information recorded more than  30  minutes  earlier  may  be erased  or  otherwise obliterated.

This was most likely in response to the 1979 incident that occurred on TWA flight 841 where the pilot was accused of improperly extending flaps during cruise but had erased the CVR when they landed,  so they had no proof. At the time CVR's were still fairly new and pilots balked at having their conversations recorded for privacy reasons, so it was common practice to erase it after each flight. There is still some concern over privacy issues since in some situations the recording can open the pilot up to legal liability.
There are really only a handful of cases where a longer recording would have been useful, most of which involved pilot incapacitation. In 2014 EASA proposed extending the requirement. The European Cockpit Association, which represents pilots released a position paper .pdf stating that they would only support the extension if there were also systems in place to ensure that only the pertinent portions could be used and any other conversation could not be leaked to the public or used in jurisdictions where there are no legal requirements to maintain pilots' privacy.

ECA  stresses  the  following:

Pilots  submit  to such  recording  under  the  strict  condition  that  the  CVR  data is  to be  used exclusively by  accident  investigation authorities in  the  context  of  their  safety  investigations.  Pilots  are  one of  the few  professions  that  agree  to  being  recorded  at  their  workplace  and  the  consequent  infringement  of their  privacy

National  and  European  legislators  recognise  the  need  to  protect  CVR  recordings  (Reg.  996/2010). However,  despite  various  legal  provisions  at  EU  and  national  level,  as  well  as  best  practices  in many  airlines,  CVR  data  or  their  transcripts  have  too  often  leaked  to  the  public  and  media , exposing  data  with  private  and  personal  content  –  sometimes  the  last  minutes  of  the  crews’  lives  – to  a  wide  audience,  generating  speculation,  interpretations  and  apportioning  blame  –  in  a  way  that may  be  far  removed  from  what  actually  happened,  what  contributed  to  the accident  and why.

This  inappropriate  use  and  distribution  of  sensitive  CVR  data  beyond  accident  investigation agencies  negatively  affects  Just  Culture  and  the  safety  improvement  efforts  in  Europe.  Extending CVR duration would increase the  quantity  of  data  available for  misuse  significantly.

Leaking  of  CVR  data  results  in speculation that  increases  the  pressure on  accident  investigators,  on the  judiciary  to  act  quickly  to  hold  accountable those  ‘responsible’,  and  on  other  authorities  or  public figures  to  come  up  with  quick  answers,  rather  than  waiting  for  the  Final  Report  to  be  published  and generating  mature  safety  improvements.

Increasing  CVR  duration  would  also  increase  the  data  that  is  potentially  available  to  the  airline management.  While   many  companies  in  Europe  have  internal  procedures  –  and  sometimes agreements  with  the  pilot  representatives  –  in  place  to  ensure  sensitive  data  is  not  misused,  this  is not  the  case  for  all  companies.  Hence,  an  increased  recording  time  –  combined  with  very  powerful digital  storing  facilities  and  the  possibility  to  cross-check  CVR  and  FDM  data  –  would  also  increase the  scope  for  (un)intentional  (ab)use  of  such  data  by  company  management  for  other  than  safety purposes  (e.g.  any  form  of  disciplinary  measures).  Although  this  would  not  be  in  line  with  EU legislation,  not  all  airlines  are  as exemplary  as  some,  and not  all  legislation is adequately  enforced.

Increasing  CVR  duration  on  European aircraft  also increases  the  risk  of  CVR  data being  used  –  and potentially  made  public  –  by  non-European  authorities,  which  are  not  bound  by  EU  legislation  and the  protections  contained  therein.  This  is  the  case  especially  for  long-haul  operations  (at  which  an increase  of  the  recording  time  is  actually  aimed)  where  the  majority  of  the  flight  is  outside  Europe.  If an  accident  happens  outside  Europe,  the  national  safety  and  judicial  authorities  will  be  entitled  to seize  the  CVR  and  will  be  bound  by  their  own  local  laws,  by  local  political  considerations,  and general  public  pressure.  –  This  would be  an  unintended  –  but  very  real  –  consequence  that  must  be taken  into  account.

I'm trying to understand the logic behind FAA's 2 hour rule.

@Firee I'm not sure if there is any specific "logic" behind it. Probably just an arbitrary number that was agreeable to everyone. It's obviously not a technical limitation. You can get a micro SD card that's smaller than a postage stamp and holds 128 GB of memory. That would be many hours worth of voice recording.

It's a little confusing. The CVR must record up to 2 hours minimum per FAA regulation - but the pilot can at-will delete everything except the last 30 mins? Is that right? Why not just only record 30 mins and have it auto-purge anything older?

With today's technology in memory storage, where simple voice
  recorders can record virtually endless durations, why are CVRs limited
  to only 2 hours. Is it the eternal "cost vs benefit" reason?

This is at least partially the result of the fact that CVR's (and FDR's alike) do not necessarily include the latest and greatest tech out there. As mentioned in the comments, while they are flying today they were not designed today, last week or even last year. The FAA has some very strict regulations on CVR/FDR from a storage stand point (you can check out this related question for more info). It's hard enough to get things approved for use as is, there may be current efforts out there to integrate better storage (and we have seen it slowly) but chances are you will see today's tech in airplanes in 5-10 years, not next week. Of course historically this may have been a data medium limitation and over the years the 2 hours has been found to be sufficient and has become a standard.

Wouldn't more recording provide greater insight to investigators in
  case of any disaster?

Generally speaking, no. While there are of course cases that can refute this, the overwhelming amount of aviation accidents happen in a relatively short period of time. If we look back at the history of aviation accidents (for which there is a great deal of data) the chain of events generally occurs over minutes not hours thus recording 2 hours of data prior to an impact is more than enough. If you watch any analysis of an investigation (there are a variety of shows out there on it these days) you will see that more often than not they are analyzing the last minutes of flight data and possibly the conversation that lead up to and occurred during that time.
We have seen a great deal of tech progression in CVR/FDR's over the years. The earliest ones were tape and some even had a primitive system that physically punched data onto a metallic strip. This slowly moved to magnetic tape and now some digital tech has been integrated. It's not that it won't happen it just won't happen overnight.


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Would it help airlines, if they knew passenger weight before hand?
Its known that pilots and technicians calculate the weight of the plane once everything is loaded, then they can decide on how much fuelling etc. needs to be done.
Would it help airlines, if they knew the weight of all the passengers before hand, say at the time of ticket booking. Having that information, would it help them in optimizing the amount of cargo/fuel etc for the flight?

While knowing exact weights wouldn't hurt, CAAs have defined average weights that are known at booking time (based on gender, age & time of year of the flight) that they use to calculate CG. See this question and this one.

An airline that routinely asked for passengers weight would quickly lose lots of business to other airlines.   Then they'd soon have nothing left to "optimize".

@abelenky airlines using small aircraft (like remote parts of alaska or something) do routinely weigh their passangers. It just makes so much more of a difference in small aircraft where the weights don't even out as easily as in a bigger jet.

@abelenky People already have to go through body scanners, metal detectors and sometimes take their shoes off. Seems like stepping on a friggin' scale ought to be the least of their worries. It's not like they're going to announce the weight to everyone. But I'm sure you're right. People would freak. Maybe they could just hire the guys from the carnival that guess your weight

Despite of the "delay" during the check in procedures, it would be safer than the average companies usually use.
For instance, the latest FAA guidelines on aircraft weight and balance control set individual passenger weight averages at 190-195 pounds for adults and 82 pounds for kids, depending on whether it's summer or winter. (Based on the assumption people wear heavier clothing in winter.)
I have read an article, and there are more pieces of information.
Airline begins weighing passengers for 'safety'

"it would be safer": It would be better if you could explain why, and for which type of aircraft, as the ratio between pax and fuel mass varies a lot between aircraft types. Also weighting passengers may be a smooth step towards a weight-proportional ticket price supported by a non significant safety improvement.

source: Stack Exchange

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sort: votes


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How long should a boarding pass be preserved, after the trip? Is there any FAA mandate on the same to make any claims later?
Ok, i'm not sure if this is relevant to AviationSE, but my query is as a passenger.
How long should a passenger preserve their boarding pass after their trip? This is with view for making any kind of claim on the Airline, be it for lost luggage, or injury during the trip, or any thing else. Is there any relevant FAA guideline or rule on the same?

I think this would be more suitable for travel.stackexchange.com as it deals more with passenger aspects than aircraft.

If you have arrived approximately in time, picked-up your undamaged luggage, passed immigration and customs and doesn't want to use an airtrain (or something similiar) you should be able to safely discard it.
Personally I tend to keep them as holiday memory, so I miss the old style tickets/boarding-passes from the 90ies :)

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Why are lavatories located near the exits of an airplane?
Is there some scientific or technical reason to locate the lavatories near the plane exits? Wouldn't it create problems during evacuation, if the swing open doors gets unlatched etc on forced landing or some minor crash etc.

I disagree slightly, they're normally near the galley, which some exits are near to. It's easier to have everything that's not passenger seats together where possible from a plumbing and electric point of view. This is also where the crew are which is useful. Also emergency exits can't have seats next to them so putting them near the galley means more seats.

I can't think of a plane with a lavatory door that swings out. I've only seen bifold doors that fold in. The only doors in the cabin that swing out are crew rest areas

so you can pee on your way out when there's an emergency.

There could be numerous reasons,
Putting them near the galley centralizes non seat related things. It also allows you to run less piping as you can pump the same water to the sink in the lav as you would to the galley.
They may be located in a place where a tank can easily be fitted beneath them so as to minimize the amount of piping needed from unit to holding tank.
They are generally a convenient way to segment cabins as they provide an inherent wall (think between first and coach).
As for an emergency situation, Lav doors can generally be locked from the outside (I have seen the little metal flap above the slide often opens and allows you operate the slide). Its common place to do this prior to takeoff and landing. I would think its part of the emergency decent checklist as well so as to keep them shut. There is a discussion on it here.

And of course, there are obvious reasons to have the galleys near the doors, for ease of loading supplies.


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Can new technology help planes dodge turbulence?
With so many technological advancements happening in the aviation industry, will it be possible for airlines to smoothen the effects of turbulence, as turbulence cannot be eliminated?
The following news indicate the same:
Smooth talk: How Qantas is ironing out the bumps
Feathers in flight inspire anti-turbulence technology

As a passenger I enjoy turbulence. I think it adds a little bit of excitement to an otherwise boring hours-long flight.

Are you asking about alleviation systems ?

Dodging, as in avoiding?

@kevin Do you like riding horses? :P


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What are these elements on the back of a Boeing 737?
I forgot the model of that plane but I believe it's a 737.
I labeled each element for clarity.
What are they?
Click here for high-res.

① Main outflow valve door

(Source)
A valve used for controlling the pressure in the cabin. Air is pushed into the cabin by the air conditioning packs, and exits by this hole. The flow can be adjusted using a valve which is located behind this door.

(Source)
The valve opening is controlled by the pressure controller when the automatic mode is selected, and by the crew when the manual mode is selected.
The design of the door includes teeth to decrease the aerodynamic noise, by better mixing air from the cabin and air ram air.
For more details about the air system, see this answer.

② Safety pressure relief valve

(Source)
This is one of the two safety valve used in case the main valve mechanism is jammed or ineffective. It's like a safety pressure relief in a pressure-cooker.
It limits the pressure within the cabin below a maximum value, to prevent pressure to damage the cabin vessel and/or create discomfort for the passengers.

③ Drains

(Source: Question)
Unknown function drains. I believe they are used to evacuate flammable fluids leaking from the APU.

④ Tail-strike assembly:

(Source)
This tail-skid is used to limit the contact between the aft section of the fuselage and the runway. It absorbs some of the tail strike force. While I'm not sure for the B737, on other models (B757, B777) the tail-strike assembly contains a sensor to alert the crew of the strike occurrence, by displaying a message on the EICAS (thanks to @RalphJ for questioning).

(Source)
The intensity of tail strike force is registered by the color indicator. A force higher than the maximum permissible hides the green strip and requires a maintenance check before the next take-off.
This strip is checked during the pre-flight inspection (walk-around) to prevent flying with a possibly damaged aircraft.

⑤ APU drain mast.

(Source: Question)
Drains oil from the forward accessory and the compressor bearing of the APU.

⑥ Aft drain mast.

(Source: Question)
Heated drain mast, part of the water system, and used to evacuate water and waste from the aft galley and the lavatory wash basins ("gray water"). Schematics of the B737 NG water system:

(Source: B737 NG General Familiarization)

@RalphJ: I've no document for the B737 tailskid, but this page explains how it works for the B757. I assumed, maybe too quickly, the B737 could be retrofitted. Reading this Boeing publication, I see no mention of the sensor for the B737, so I'll update my post.


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Starting on the left magneto only - why?
I had been flying a PA-28 Archer III for quite a few months before I sat down to properly read through the POH. Something stood out to me about the starting procedure (emphasis mine)

Open the throttle lever approximately 1/4 inch. Turn ON the
battery master switch, alternator switch, left magneto switch and the
electric fuel pump.
Move the mixture control to full RICH, verify the propeller
area is clear and engage the starter. When the engine fires, release
the starter switch, and move the throttle to the desired setting. Turn
ON the right magneto switch. Check the oil pressure for a positive
indication.

Having previously flown aircraft where a key operates the starter, and that key has to travel past left, then right magneto to the start position I was starting with both Mags in the ON position (For those unaware, the Archer III varies in that the left & right magneto are operated by a rocker switch).
The obvious answer to the question of "Why start the engine with only 1 magneto live?" is "Because that is what the POH says to do!" - I am nonetheless interested in the electrical or mechanical reason why? Or perhaps there is some safety aspect at work?
Does anyone know the details?

The reasons seems to be that only the left magneto is equipped with an impulse coupling which delays and intensifies the spark during engine starting:

Many opposed reciprocating engines are equipped with an impulse coupling as the auxiliary starting system. An impulse coupling gives one of the magnetos attached to the engine, generally the left, a brief acceleration, that produces an intense spark for starting. This device consists of a cam and flyweight assembly, spring, and a body assembly.
[...]
The impulse coupling has performed two functions: rotating the magneto fast enough to produce a good spark and retarding the timing of the spark during the start cycle. After the engine is started and the magneto reaches a speed at which it furnishes sufficient current, the flyweights in the impulse coupling fly outward due to centrifugal force or rapid rotation. This action prevents the two flyweight coupling members from contact with the stop pin. That makes it a solid unit, returning the magneto to a normal timing position relative to the engine.

(flight-mechanic.com on Impulse Coupling, emphasis mine)
On an aircraft with key operated ignition (where the start position comes after both), the right magneto is grounded while you hold the key in start:

Most airplanes have an impulse coupling on the left mag only. During engine start, the ignition key grounds out the right mag, so only the left mag provides spark. The timing of the spark from the left mag is retarded (later than usual) during engine start so the engine will start easier. Once the ignition key is released from the start position, the timing of the spark is restored to normal, and the right mag starts firing.

(askacfi.com)

The POH of the Archer III I fly one states that both mags should be on for startup. Maybe newer versions ground the right mag when the starter is engaged ?

Either that or the right mag also has an impulse coupling. But more likely the right mag is grounded by the starter. The system description in the POH is probably not detailed enough to include this information, is it?

@QuentinH this is interesting. The checklist which is taken from the one I fly just specifies "Mags On" but the POH I was looking at was just one I found online for an Archer III. I shall have to check the actual POH of my aircraft next time I fly.

Magnetos perform badly at low speed, and their timing will be too advanced during start, making the spark too early. Usually the left magneto has an impulse coupler, which is a coil spring driven cam, to spin up the magneto and retard the ignition so it is at top dead center, otherwise the engine may spin backwards which is bad. The right magneto doesn't typically have an impulse coupler, so you leave it off. In a key system the start setting grounds the right mag for you.

This raises the follow-on question of how much, if any, damage or extra wear "quite a few months" of turning on both magnetos on this particular aircraft this might have done.

Probably very little @JdeBP.

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text:
Why did the Soviets not make radio contact with Korean 007?
I was reading recently about the shootdown of Korean 007 and it is clear that it was very tense times between the American and Soviet governments.
The one point which struck me as weird throught the entire narrative was that it does not appear that the Soviets made any attempt to contact the Airliner other than firing some cannon shots. Was this usual for the time? Was there no way for them to contact the Korean airliner?
The military pilot possitively identified the target, but it was the Soviets belief that it was a spy plane disguised as a civilian airliner - did this not warrant at least trying to contact them?

Did the Boeing pilots fly over Soviet airspace by error or accident...?  Or were they really following a route intended for a spy mission...?

@xxavier They were supposed to be following a route which went close to soviet airspace but it seems their A/P was in HDG not INS mode and so they strayed twice into soviet airspace. The second time they were shot down.

Legal aspect: The Downing of Korean Air Lines Flight 007. "The military pilot positively identified the target", it seems the closest distance between military and KE007 was 2 km. Not really a visual identification, though at least 20 minutes were available for one.

The report of the completion of the ICAO fact-finding investigation confirms that not attempt to contact the aircraft was made:

No attempt was made by the USSR to contact the crew of KE 007 by radio on the
distress frequency 121.5 MHz or on any other VHF or HF frequency.

The report also contains a summary of an interview with the pilot of the interceptor plane. He said that he did not have time to contact KE007 because he would have lost connection to ground command:

The ICAO team was unable to meet with the SU-15 interceptor pilot in February 1993,
but was provided with articles published by Izvestia in January 1991 containing extensive interviews with
him. The contents of the articles were confirmed as authentic by representatives of the Russian
Federation.  [...]
He also reported that
he did not try to establish radio contact with the aircraft because he would not have had the time to do
so, he would have had to tune to that frequency and in so doing he would have lost contact with his
ground command.

(emphasis mine)
The pilot also reported that he did not know it was a passenger aircraft:

The interceptor pilot stated that 1983 was a difficult year for Soviet interceptor pilots in
the Far East region as there had been numerous intrusions into Soviet airspace by military aircraft of the
United States. [...]
At that stage he could more clearly see the aircraft, but could not identify its type
as Soviet pilots did not "study" foreign civilian aircraft. The flashing lights (rotating beacon) of the
aircraft were on. He said that he had no idea that it was a passenger aircraft.

The question why nobody on the ground attempted to contact the aircraft still remains. As far as I could find, there is no definitive answer to this. The following is somewhat speculative.
Initially, the USSR believed the aircraft to be a US spy plane (RC-135). While there was some doubt about this (someone even suggested it could be a civilian airliner), the failed attempt to intercept the aircraft over Kamchatka created more confusion among the USSR air defense command personnel. By the time the aircraft approached Sakhalin Island, the situation was already too time critical to further investigate the identity of the aircraft.
That is my interpretation based on the following points of the analysis summary in the report:

3.23 The proximity of an RC-135 (a United States intelligence aircraft) and KE 007 northeast
of Kamchatka Peninsula resulted in confusion and the assumption by the USSR air defence that the
aircraft proceeding towards the USSR was an RC-135.
3.24 USSR military aircraft attempted to intercept KE 007 over Kamchatka Peninsula.
3.25 Information was freely available to flight crews that an aircraft penetrating prohibited
areas of USSR sovereign airspace over Kamchatka Peninsula and Sakhalin Island might be fired upon
without warning.
3.26 The USSR air defence command centre personnel on Sakhalin Island were concerned with
the position of the intruder aircraft in relation to USSR sovereign airspace as well as its identity.
3.27 The time factor became paramount in the USSR air defence command centres. as the
intruder aircraft was about to coast out from Sakhalin Island.
3.28 Exhaustive efforts to identify the intruder aircraft were not made, although apparently
some doubt remained regarding its identity.

The second part of this is more what I was speculating about (Why no attempted ground contact). There was also the unfortunately timed climb to FL350 which the military pilot interpreted an avoiding action to make the much faster jet fly past.

@Jamiec Yes, that is the more interesting part of the question. Unfortunately, the USSR was not very cooperative during the initial investigation, which is why information about what was going on in the command centre is sparse. The quote above is already from the revised report based on the additional information provided by Boris Yeltsin in 1992. Maybe some will find a better source with more info...

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Why cycle the magnetos before engine shutdown?
Inspired by this question asking about shutting down a light aircraft engine I realised there is another ritual which I do, but have long forgotten the reason why.
Having parked a light aircraft, and switched off the electrics, with the engine still running I always check left and right magnetos, similar to the magneto drop check done as pre-flight checks.
I don't really pay much attention to the RPM, I do it because I've always done it. It's not (as far as I remember) on my shutdown checklist - and I'm starting to wonder why I do it.
Is this necessary? Something in the back of my mind is saying "prevents mag fouling". What is the real reason to cycle Left & Right mag pre-shutdown?

Pay attention to the drop and look for roughness. If you didn’t lean enough on your flight, you may have fouled the plugs. It’s better to know that when you shut down rather than when you get to the runup area for your next flight.

So called mag fouling normally refers to spark plug fouling, and that is normally addressed during run-up by leaning the mixture to a hot and lean mixture, at a reduced power setting (like 1900 or 2000 RPM) and running with both mags selected for several minutes.  Then the mag drops are retested.

This is a hot-mag check to verify that when you shut the engine down, you are really putting it in a safe(r) state. Think about how the mag-switch works, when you switch to R or L, it grounds the P-Lead on the other side (so switching to R grounds the P-Lead on the Left side). If you don't see the RPM drop, you may have a hot mag on that side.
An un-grounded mag is a dangerous situation in that it can cause the aircraft engine to turn over if you accidentally (or intentionally) move the prop when you are parking the aircraft, or when somebody walks by and runs into your prop.
So during this mag check you are only looking for an RPM drop or a change that tells you that the mag is shut off.

That’s what I was taught, but really, isn’t testing each mag for a drop doing the same thing? It won’t drop if there’s a ground. I guess that wouldn’t verify no ground in the switch itself when set to OFF.

Yes, the reason you do it at shutdown though is that you've just finished flying the aircraft and you are about to move it (possibly push it by placing your hands on the prop). You want to be sure that if you accidentally move the prop it doesn't kick over. You want to make sure that a P-Lead didn't disconnect in flight, the run-up is for checking mag quality and plug fouling, the shutdown is for checking p-lead.

Maybe this might be better suited for Electronics, but what is exactly meant by ground? What is the P-lead connecting to when forcing the flow of electricity to be redirected elsewhere? Is it earth's grounding, or the casing of the fusilage?

@HeavenlyHarmony It's referenced to the negative side of the battery, which I believe is also grounding the fuselage/airframe (but this probably depends on the aircraft, a composite aircraft wouldn't have a grounded fuselage).

You are doing it wrong if you are just cycling left/right/both.  It is a hot mag check, not a mag function check like on a runup.  You are supposed to cycle them to OFF and then back on to BOTH before shutdown and listen for the sound of combustion stopping in the exhaust. You do it after the engine has had time to cool down and while the engine is at idle to avoid backfires.
Remember that magnetos are disabled (shut off) by grounding out the primary circuit.  If the P lead, the ground out wire, to the ignition switch breaks, the mag is prevented from turning off and remains live.  You are making sure they are grounding out and really shutting off so you don't have an undetetected live mag after shutdown.  You have to do this because shutdown is done with the mixture cutoff and if the one mag is live after being turned off you won't know it, and a surprise could occur if the prop is moved later and the mag fires with residual fuel mixture in the cylinders.

I don't think you adequately explain why it is wrong to cycle left/right/both. My understanding is that if there's a mag drop on left, and another one on right then it proves both mags are grounding properly as well as turning the key to off. Turning it to off means you get fuel in the exhaust system.

To get a noticeable mag drop you have to have some power on.  This check is done just before shutting down, when at idle.  Yes a bit of unburned fuel gets through, but when done at idle after the engine's cooled down it's not sufficient to cause a back fire and when you put the mags back on you're back to normal.  You only have them switched off for a quarter to half a second.  I've been doing it for 40+ years and have never had a backfire.

This is going to give the same reason as Ron Beyer's answer. I'm only writing another because I found his a little hard to follow and I'm going to try to explain it differently. It's nothing to do with mag fouling at all.

The magnetos are wired up so that a failure of the switch or wiring leaves them live (on), unlike most electrical devices which are wired to be off if they fail. This is normally what you want because if the wiring fails in-flight, you'd like the magnetos to keep working. But it can cause a dangerous state, where the magnetos are stuck on when you think they're off. If you swung the prop in that condition, it could fire when you're not expecting it.
So one at a time, we switch a magneto off, and check that the RPM appears to drop, and that the engine sound changes. The sound is more important - as John K says, the drop is small at the kind of RPM you do your mag drop test, and hard to see unambiguously on the gauge. This way, you know that switching it off really does isolate the magneto, so you know that when you turn both off after stopping the engine, the propeller is safe.
It's not so much for your benefit as whoever will touch or fly the aircraft next. Even so, you should always treat a propeller as live. If you have to swing it (e.g. to inspect it), do so as if you were hand-cranking the engine, keeping well clear and making sure your arm comes out of its path.

I am not sure what I meant. I think I was answering a different comment.


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Why are airspaces depicted in AGL?
Generally we fly under the rule of QNH which means our IA is above mean sea level. And as we all know airpace limits are charted in MSL. Then, why the definitions of airspaces are they (class C, D and E) depiceted in AGL?

Can you give an example of where you see this? In Germany, only the airspaces directly touching class G are in AGL, all other airspaces start in MSL. The reason is that class G goes up to 2500ft AGL, so all touching airspaces need to start in AGL as well.

@SentryRaven In the AIM, class C airspace is explained like this `Generally, that airspace from the surface to 4,000 feet above the airport elevation ...' this where I was confused.

Which AIM is that? Control Zones in Germany have a MSL upper limit. But we don't have class C CTRs, only class D.

It's America's.

Well, if you have airports at different elevations, and you want a 4000 feet high CTR around each airport how else are you going to define it?

Now I got it. Thanks guys

A description in the AIM is not really the same as a definition

You're confusing the airspace height with airspace altitude.
The definition of Class C (in the US) is

3-2-4 (a) Generally, that airspace from the surface to 4,000 feet
  above the airport elevation (charted in MSL)

If you look at chart for the Class C for Colorado Springs (elevation 6,187), the surface area of the airspace goes up to 10,200 ft MSL, approximately 4,000ft above the airport elevation of 6187.


text:
Why does only class C airspace have an "outer area"?
There is an area called "outer area" near class C airspace. As described by this AIM:

Though not requiring regulatory action, Class C airspace areas have a procedural Outer Area. Normally this area is 20 NM from the primary Class C airspace airport. Its vertical limit extends from the lower limits of radio/radar coverage up to the ceiling of the approach control's delegated airspace, excluding the Class C airspace itself, and other airspace as appropriate. (This outer area is not charted.)

As it is not charted and there is no FAA regulations about outer area, I would think it could also be set near class B or D airspaces. Why don't any other airspaces but only class C airspace has the outer area?

The Class C outer area is the airspace surrounding Class C airspace out to 20nm, and from the lower limit of radar coverage to the top of the controller's airspace.  The outer area is not charted, although you can see in the white boxes (in the chart below) adjacent to Class C airports that you can initiate communication within 20nm.

ATC offers Class C services (e.g., flight following) on a workload-permitting basis to participating aircraft operating in the outer area, and aircraft in 2-way radio communication will receive IFR/VFR aircraft separation services.
So you can think of Class C airspace as 3 concentric rings: the 20nm outer area, the 10nm shelf area, and the 5nm surface area.
Source AIM 3-2-4

Thanks. However, I found the answer by myself. Since the Class D airspace doesn't offer radar service, and the Class B airspace is so busy there is no reason for these airspaces to have the outerarea which offers radar services on-request. My question was so stupid.

I think its because Class B extends out 30 miles. Wouldn't make much sense to have an outer area that extends to, what?, 40nm.

ATC offers flight following in all E airspace, though, not just the C outer area. The difference is that this will be done by an Approach facility, same as in and under B airspace (actually, inside the veil), rather than Center. Officially, there is little if any difference between the two, at least for VFR pilots, aside from who you call.

@StephenS Flight following is only available where there is radar coverage.

The outer area surrounding classy airspace is not actually Class C  airspace, but a procedural area associated with the Class C and not charted.  See Note 4 of AIM 3-2-4.  This area is not considered Class C airspace, but VFR flights making use of approach control or IFR flights inbound and outbound of the Class C are still under the control of approach control for that Class C airspace.

This answer does not address the question. OP knows there is such a procedural outer area; the question is why such an area exists on the periphery of Class C airspace, but not Class B or D.

@randomhead, I agree, but the same comment could apply to the accepted answer with 16 upvotes.

authors: بيرق البرقاوي


text:
Why do super sonic fighter jets have narrow waist?
Some of the supersonic fighter jets (such as F-4 Phantom and F-5) have narrow waist on their fuselage.

Why do these fighter jets have narrow waist?

See this question about the area rule.

It is likely due to application of the Area rule, which helps to reduce drag due to shock waves in transonic and supersonic flight.
It basically is an attempt to keep the cross-sectional area of the craft from varying rapidly as you move along the length.  So at a point where the wings area is increasing a lot, the area of the fuselage may be reduced to compensate.
This reduction of area is mainly intended when these airplanes fly at transonic speeds (0.8-1.2) but not when flying at supersonice speeds where a front shock wave is created.

I was not aware of the area rule for transoceanic fly.  Thanks for detailed answer.


text:
Safety measures to prevent pilots causing passenger planes to stall
Why is it possible for pilots of commercial airliners to execute manoeuvres virtually guaranteed to cause a stall?


text:
Does kerosene have a higher octane value than gasoline?
One of my coworkers says his chemistry teacher told them (a long time ago) that kerosene has a higher octane value than gasoline. My understanding was always that aviation gasoline has octane value above 120, but it is really gasoline, while kerosene is more like diesel fuel. What is the truth?

I'm not sure what you are asking.  Do you understand what octane means?  I think you might be confusing avgas octane with the energy content of a fuel. E.g. diesel has a lower octane than gasoline but a higher energy density.  As far as I know, kerosene is only used in jet engines, therefore the octane rating is not relevant.  About the only thing answerable in your question is yes, kerosene is more like diesel.  You might want to read those articles then reconsider your question.

No, I'm not confusing octane with energy content. If, theoretically, one uses kerosene in an internal combustion engine, will the engine suffer from knocking?

Related: Why do jet engines use kerosene rather than gasoline? and octane rating.

Octane rating is a measure of how well a fuel resists detonation, which is the premature explosion of fuel in an engine cylinder before the spark is applied. This is relevant for spark ignition engines which use gasoline type fuels like avgas.
Kerosene has a very low octane rating, somewhere around 15, and isn't a good fuel for spark ignition engines as it would detonate on compression. This is why kerosene and diesel are used in diesel cycle engines which rely on the spontaneous detonation of fuel under pressure. Kerosene is not typically used in internal combustion engines, however in aviation there are turbo-diesel piston engines which run on Jet-A1.

Do you have a reference I can show my coworker?

Try googleing "octane rating of kerosene", brings it right up.


text:
What is this tube along the right side of a Blue Angel?
I was at the Museum of Flight in Seattle, WA, yesterday, and came across a Blue Angel aircraft, pictured below.

Along the right front of the plane, there is a small tube that is capped with a silver cap.

I thought at first that this might be a refuelling point, but (A) I didn't see any real purpose to have mid-air refuelling on a Blue Angel, and (B) it doesn't seem like a great place to refuel (since it seems like it could easily obstruct the pilot's view).
(I looked online at some images of Blue Angel aircraft and realized there are several makes. However, I didn't find this particular tube and cap on any of the other makes. (example) In fact, I don't even recall what make of Blue Angel this craft actually is.)
What is this tube at the front of the jet, and what is it used for? Why does it only appear on some makes of the jet?

Isn't it an A-4F Skyhawk?

It is a refueling probe.  The A-4 was very small and the probe was fitted where it could fit.

You need to look at it the other way. It would be extra work to modify aircraft for display team, so it is equipped exactly like a standard combat one.

@JanHudec Yes, but also consider that for some of their ferrying flights it was more convenient to do in-flight refueling, plus it maintained the pilots proficiency rating for the procedure.

I haven't seen a Blue Angels performance, but the Thunderbirds make a point that their airplanes are a paint job and a weapons load away from being combat ready.  A refueling probe may not have a purpose on a demonstration aircraft, but it's part of the standard equipment.

@Mark -- besides, refueling gear might be handy if they ever have to take a long trip overseas :)

The aircraft is the A4 Skyhawk and the probe is for air-to-air refueling.

As you can see, it doesn't really impede the pilot's view which in any case, is concentrated on the refueller.
You can always spot a refuelling probe. For NATO aircraft, and most others, they always have the same tip and are the only appendages which look like this.
The Blue Angels used it since transits to various air shows exceeded the range and air-air refuelling is cheaper and more effective than landing, refuelling and taking off again.

Actually, USAF and USN fighters use different refueling hookups. Navy fighters use the extended refueling probe on the plane with a "hose and drogue" on the tanker, shown in your image. The refueling plane can be further away, but making and maintaining contact is pretty much 100% pilot. The USAF adopted a "flying boom" that connects to a port behind the cockpit; this approach gets the plane further below and underneath the tanker, where the refueling link is then easier to maintain, and the pilot merely has to hold still while the boom operator makes contact.

The KC-10 in your picture supports both refueling methods with separate systems; you can see the V-tail of the flying boom tucked up just behind the tail. The KC-135 uses the flying boom as its primary refueling method, but can support Navy fighters with a drogue adapter either attached to the boom or to outboard pylons.

It's a refueling probe. Below is a picture of it in action:


text:
Why do airlines park their planes out in the middle and ferry passengers to the terminal by bus, even during non-peak hours?
There are numerous occasions, especially during late night flights, when hardly there is rush at the airport, the pilots park the airplane out there somewhere, and ferry the passengers by bus. Is it a big trouble to take the plane to the aerobridge and then take the plane to the parking spot?

it's the airport operator that decides where the pilots park based on -> 2. the agreement between the airline and the airport operator might stipulate that the airline parks there

I think it's also a matter of fees: parking further away is cheaper than parking in the gate's immediate vicinity.

Related

@Pondlife I think its the opposite

@Firee Yes, I think so too. It's related, but not a dupe.

It is a duplicate and the answer states parking overnight on the bridge is more expensive.

@h22 Why can't they drop passengers at the bridge and then taxi to their favourite parking spot?

An airport will have a menu of charges for the services it provides to airlines.
Here is one Schedule of Charges for London Heathrow, for some of these services. Probably you can find further examples via their Conditions of use page.
Some of these charges are unavoidable - landing fees, for example - but others will be subject to agreement.
An airline can save money by opting for a cheaper option in certain cases.
If you've ever watched successive plane-loads of Ryanair customers climb out of their 737s into horizontal rain to trudge across 100m-wide puddles to the terminal, and each subsequent shipment of shivering human cargo queue at the steps as the wind whips the standing water up to knee-level, while every other airline during the same period uses a bus to deliver its passengers, you'll have had a very visible indication of they way airlines can choose to pay for particular services - or not.


text:
Why do Boeing and Airbus have distinctively different nose designs?
Boeing aircraft generally have a pointy nose, which seems to me to imply better aerodynamic qualities, less drag etc. Airbus aircraft on the other hand have rather bulbous noses.
Is this difference to give Boeing and Airbus aircraft a consistent, distinctive visual appearance, or is there any specific aerodynamic reason for the different designs?

This image is only an example and my question is not about any specific model.

I would highly doubt the engineers at Airbus ended up with the design (of the nose) they did because of "better identification"

"More pointy" isn't necessarily synonymous with "lower drag"

@JonStory related

Wow...would love to know why this got down voted

aerodynamics involve the design of the whole fuselage, including the tail.

this is a valid question.  similar questions regarding individual aspects of aerodynamic design have been asked before.

This is because American and (British) cats tend to be pointy-nosed cats and continental cats tend to be round-headed, blunt-nosed cats. So, just like the cats, the aircraft are different.

Drag may be different at different speeds for both. Should we assume you want to know at cruise speed ?

@mins I want to know generally, the philosophy behind the two designs..

With the 747 vs. A380, I think it has more to do with the flight deck on the 747 being located on the upper level, while the flight deck of the A380 is on the lower level. Comparing an A330 vs. a B767, it actually looks like the 330 has a 'pointier' nose.

@reirab : I am not comparing 747 vs. A380, but am looking for the general philosophy and the advantages of each design, else why else would they be different

@Firee Right. I was just saying that I'm not sure your implication that Boeings generally have 'pointier' noses than Airbuses is actually true, aside from the 747 vs. A380 case. It doesn't appear to be the case when comparing the A330 vs. B767, for instance.

Distinctly different?  Surely you're kidding?

@reirab: It is true for the 737 vs. A320... but that's because the 737 has the nose of the 727, which has the nose of the 707, which has the nose of the 367-80, which was designed back in the early 1950s.

The answer to this is, in part to do with corporate culture and part aerodynamics.
The corporate culture and history part is that Boeing have always built their noses that way and senior engineers have a tendency to return to designs they have used successfully before. If you look at the nose of a 747 and the nose of a B-17 you'll see some distinctive similarities that follow through all the major Boeing aircraft. This isn't surprising as lead designer of the 747, Joe Sutter, started working for Boeing on the 707 project under the direction of the engineers that designed the early flying forts.
Airbus is a newer company with a different corporate culture. They tend to embrace new design techniques like CFD computer modelling to a greater extent and this leads to slightly more efficient but less aesthetically pleasing nose and wing designs.
The science side is related to the speed that modern airliners travel at (around 0.85mach). At these speeds aircraft begin to encounter a phenomenon called 'Wave Drag' which is the incremental build-up of compressive shockwaves along the wings and fuselage as the aircraft approaches the speed of sound. The effect of wave drag is to drastically increase the overall drag affecting the aircraft, increasing the power output required from the engines.
There are several methods of combating wave drag, the first of these is the swept wing that has been a feature of trans and supersonic aircraft since WW2. The optimum angle of wing sweep is determined by the cruising speed of the aircraft. A more recent innovation is the Transonic or 'Whitcomb' Area Rule which states that:
"Two airplanes with the same longitudinal cross-sectional area distribution have the same wave drag, independent of how the area is distributed laterally"
Wave Drag can be reduced by attempting to match the cross sectional proportions of an aircraft as closely as possible to those of a Sears-Haack body (an aerodynamically perfect shape for supersonic flight) This is why Airbus planes have blunter nose. it is also why there are strange bulges under the wing roots of the A380. they are both attempts to make the planes cross-section conform to a Sears-Haack body more closely.

Welcome to the site. The pictures of Sears-Haack bodies that I can find do not look very blunt. Also, Mach 0.65 is a bit slower than most jet airliners cruise at.

A true sears-haack body is 'pointy' because it is idealised for flight at exactly mach 1. The shape can be varied by biasing the centre of mass forwards or backwards for flight above or below the speed of sound so a 'slow' S-H body will be blunter. The aerospace designer then has to approximate the cross-sectional ratios within his design.
Thanks for pointing out the typo with the cruising speed. edited to fix.

The Boeing B-29 nose looks rather blunt to me. I do not think that the nose design back then was driven by branding. Also, wave drag would not explain nose shapes - on airliner noses we will not find supersonic flow.

Actually wave drag begins to be an issue for planes travelling as slowely as 0.65 of mach. during WW2, fighter pilots in steep dives found their control sucrfaces would lock up because of it. at 0.85 it is a definate problem and the whole of the aircraft, including the nose, contriubutes to the solution.

Airbus and Boeing are not the only airplane manufacturers who see the nose shape as something to sharpen their brand. Look at the Schleicher gliders (the left picture shows an ASW-20) and compare their pointed nose to those of Schempp-Hirth, which is distinctively more blunt (the right picture shows a Discus).

The shorter nose will incur higher induced speeds, but a shorter boundary layer and less wetted surface. Which is better depends on the particular flow situation.
Or take the canopy shape of Glaser-Dirks gliders which stand out with their stretched-out shape which allows even the feet of the pilots to be bathed in sunlight (see picture of a DG-300 below). This is like a brand label.

Disgruntled Boeing engineers told me once that they spent three months optimizing the tailplane-fuselage intersection of the Boeing 767, only to have their design rejected by upper management because it looked "too much like McDonnell-Douglas". Yes, the outside shape is important to management to express their brand.

Peter, it's absolutely amazing that an airliner would be designed with "body look" in mind!  Thanks for this info !


text:
Are there any safety mechanisms to prevent emergency slides deploying inside an aircraft?
Does this kind of situation happen, or is this a test situation? Are there mechanisms to prevent inward deployment of emergency slides?

Haha. That deserves really a "lol". Which plane is that, Planey McPlaneface?

See https://aviation.stackexchange.com/questions/12952/what-does-it-mean-for-a-door-to-be-armed

Isn't that an independent raft inflated inside the cabin by accident? This image is used to illustrate such earlier incident on a DC-8. The story itself is funny (use Google translate, the account is written in quite rude style)

I know there was a crash once, back in the 70's I believe, where one of the slides inflated inside the plane and pinned a flight attendant until someone was able to cut it and free her.

@TomMcW this (also?) happened in the 2014 Asiana crash at SFO

@Ben That's probably what I'm talking about then. I just remember reading about it in an investigation report somewhere.

@Ben: It happened twice in the Asiana crash at SFO.

Yes, they can inflate into the cabin. The FAA has been criticized for not taking better action regarding this and several other escape issues. Consider what happened on July 6, 2013 when Flight 214 struck the sea wall while landing...
Here is a direct quote:

During the crash two of the inflatable chutes deployed into the cabin. The first chute, which blocked the forward right exit, nearly suffocated a flight attendant and was deflated by a pilot with a fire axe from the cockpit. The second chute expanded toward the center of the aircraft near the fire. It trapped a second flight attendant until a co-pilot deflated it with a dinner knife.

When I worked for Continental Airlines, a slide would deploy unexpectedly either while the aircraft was stationary at the gate or while the attendants were opening the door (no fault of theirs). I have never heard of a slide deploying while in flight.

Escape slides are absolutely valuable means to provide safe egress way to ground in emergency evacuation. But it is absolutely true that escape slide can be inflated inside aircraft, so that means safety device can be fatal obstacle to saving life. There were many cases that the slides were inadvertently inflated in the cabin in case of emergency landing.
I wonder why NTSB is so passive to recommend to modify the technical requirement of this emergency equipment. I strongly believe that it should not be inflated at any time inside the cabin.

Hello JINAir, welcome to SE aviation! This site prefers comments to have some authoritative reference to back up answers. The statement "There were many cases that the slides were inadvertently inflated...", will need a couple references or you will find folks will soon mark your answer negatively. Good Luck!!!


text:
Why don't the noses have the same de-icing metal surface like that of the wing's leading edge, engines, tail, etc.?
For reference, let's take the A320. The nose is painted like the rest of the body.

Image Source

There's no aerodynamic reason to have it there. In fact it's only on the windows because the pilot needs to see, otherwise is isn't needed there either.

Related: Why did most airliners have black noses in the 60's and 70's?

@ymb1 Thanks, I got them mixed up

Areas on the airplane with ice protection have it for important reasons:

Ice on the wing/empennage disrupts airflow, adding drag and making it more susceptible to stalling.
Ice on an engine cowl lip can disrupt flow into the engine, causing stability issues. If it dislodges it can damage the engine.
Ice in the pitot/static system prevents the air data system from reading airspeed or altitude properly.
Ice on the windshield can make it harder to see through.
Ice in drain lines can cause them to clog and not drain properly.

The nose is not as important. Ice will add drag, and has some risk of breaking off and damaging something. But this is not as critical as with other areas. There is also an added challenge in adding anti-ice measures, as it must interfere as little as possible with the weather radar inside. It's made from composite material, which doesn't conduct or cope with heat very well, so using either bleed air or electric heating would be an issue.

Nice answer.  I might also add that ice doesn't actually adhere as much to blunt nose surfaces so not as much will accumulate compared to wings and probes.  It accumulates the most on sharp/thin leading edge surfaces.  The A-380's inboard leading edge radius was so large it was found it wasn't necessary to anti-ice it.  They only anti-ice from the inboard engine out.

That is interesting about the A-380, do you have more info on the same, I would like to read it.

Wings need undisturbed airflow in order to create lift. Even a small covering of ice can lead to a significant loss of lift. Noses do not create lift, all ice accumulation may do is increase the weight of the airplane a small amount, which isn't a big enough concern to warrant the cost and weight of an ice prevention system.


text:
Why don't we have allocated cabin baggage space just like seats?
There is always a hassle of finding overhead cabin baggage space. Why don't airlines, divide the space and allocate it for each seat, just like they have allocated space for cabin crew and demo stuff.
This way, each seat has their allocated cabin baggage space, so a passenger can board in peace knowing their cabin baggage space is reserved.

If this question is off-topic, then to which other sub/site on Stack-exchange should I re-direct this. My question was more from a cabin design point of view, as to how practical, cost efficient, time saving would it be given the entire scheme of things. The answer this question received is really great, and I'm sure there would be other great insights, had this question remained open.

Interesting, but inane question. Because passengers have wildly varying amounts of carry on (but randomly/normally distributed), there's nothing to gain by allocating space beforehand, and a whole lot of unnecessary complexity to plan and manage for it!

Passengers do usually have some allocated space - under the seat in front of them. No-one else is going to claim that...
For the overhead lockers, a quick calculation (as @mins suggests) - seat pitch averages about 30", so there is going to be approximately a 30" slot above each row for "its" locker. On a 3-4-3 widebody, this would be ten seats sharing 4x30" of locker space, equivalent to a 12" slot each. On a 3-3 narrowbody, the six seats would share 2x30" of locker space, or 10" each. Not all seats have an accessible locker above them - eg emergency equipment storage - and there is some space taken up by the opening/closing mechanisms, so in practice it would be an inch or two less than this overall.
Meanwhile, almost all airlines give a maximum smallest dimension of their cabin bags - ie narrowest width they can fit into - of 20-25cm, or 8-10". So one standard-sized bag per person approximately fills the space given, assuming they can all stack neatly on their sides.
So, in theory, yes, you could try allocating space, one ~8-10" bag slot per person, and the overall space is available. But this would almost certainly mean putting in dividers to avoid disputes (you can imagine the disputes, right? "That man's bag is taking up some of my space!").
The dividers would mean that you couldn't put anything weirdly shaped in there - say, a walking stick - and would mean there would be problems with bags that don't quite fit the limits. At the moment, they can bulge a bit and be squashed in with everything else, so the passenger in seat 11A with a slightly outsize or awkwardly shaped bag can benefit from the fact that 12C's is quite slim, and everyone is happy, but once you have rigid dividers that becomes impossible. 12C's would rattle around, while 11A's doesn't go in, and overall the space is used less efficiently.

That's a great answer, even though the question is OT. :)

and as usual the problem isn't the aircraft, but passengers bringing far too much cabin luggage and gate crew not enforcing restrictions as well as they should and forcing people with 3-4 full size suitcases to check them into the hold at full overluggage fees as they should but letting them take the bags on board, leaving someone else to deal with the inevitable problem and irate passengers.

@Andrew: Does that mean that the current system is the best and most efficient? Also personally I find keeping my luggage under the seat in front of me, very cumbersome, and it robs me of the precious leg space commercial airlines offer these days.

@Firee I wouldn't go for most efficient, but it's probably more efficient than an allocated slot approach - assuming most people want to bring large cabin bags, which they usually do, these days. If we could reliably assume everyone had something handbag-sized at most, it'd work fine - but then, we also wouldn't have the same sort of problem in the first place.

(Also, I agree on underseat storage... but it's certainly there even if you & I prefer to use it for our legs)


text:
What is this yellow section around the cockpit window?
Saw this while boarding the flight the other day, travelling between HYD (Hyderabad, India) to CCU (Calcutta, India) on Indigo Airlines. Aircraft was an Airbus A320.
There was a yellow patch around the window. Was this because the same was repaired?

You're right. The aft no. 3 fixed window has a reusable retainer with 2 rows of fasteners- one for holding the window glass and another for attaching to the fuselage, as can be seen in this PPG document- this is the two rows of fasteners in the image.

A320 aft window, image from Cockpit Windows Technical Data from PPG Aerospace
My guess is that there was some damage to the area and the airline replaced the whole assembly and sent the aircraft before the primer could be painted over. When painted, it would look some thing like this:

A320 window, image from miles-around.de
Note: The A320 does have an emergency (sliding) window in the cockpit- however, it is in the no.2 window, the details of which can be seen in this document


text:
Can a commercial airline continue its flight if its landing gear fails to retract after take-off?
So after take-off, due to any reason, the landing gear does not re-tract, is there any standard procedure to be followed? Or can the airline continue with its flight?
Also, I would like to know any FAA regulation on the same (if any), which deals as to the procedure to be followed in such situations.

Enter "Osan" into the search field and you'll see a couple of comments that show why airliners typically will not continue the flight.

Because this can be counted as a failure, the pilots probably will be forced to land the plane and not continue the flight.

@FallenUser, there is no such thing as “counting as failure”. For every system the pilots know how well or not the aircraft can fly without it and handle every failure accordingly. Gear not retracting “just” causes massive increase in fuel consumption.

Usually not. It depends on various factors, most importantly the available fuel. If the pilot decides that enough fuel is available even after accounting for the extra drag due to extended landing gear, he can decide to continue, though this will rarely be the case as the drag penalty is too high and the aircraft speed is limited.
A case in point is the Hapag-Lloyd Flight 3378, which crash landed due to fuel starvation caused by the extended landing gear (which was kept that way as a precaution). The pilot was criticized for his decision to keep on flying instead of diverting to another airfield, and given a suspended prison sentence.

Unless it's a (very) short hop with sufficient fuel onboard and anticipated maintenance services at the destination airport, no.  As mentioned above extended gear restricts speed and increases parasite drag on the airframe.  The most likely scenario would be to report this to ATC, thence divert to a hold to either dump or burn off your excess gas until you're below the maximum landing weight, thence return to the departure airport or divert to an alternate.

Another factor would be the facilities available at the origin/dest/enroute airports. For landing gear issues a gear-swing may be required and that would require aircraft jacks/stands.
Example, I worked in an airline which operated a short sector from KUL-CGK vv. On departure KUL the landing gear would not retract. The pilots discussed this with MCC (maintenance control) and decision was made to divert to SIN where there was full capability for any landing-gear work.
Basically, an aircraft with its gear down is still safe, it will not fly as fast nor as far as planned but it is not a 'land immediately' situation.

A flight can continue, there's no regulations to prevent it, it's the judgement of the pilot in command. In most cases the drag penalty will mean the flight will run out of fuel short of its destination, but a flight could theoretically continue. If the airplane has a short hop, plenty of fuel and the emergency facilities at the destination are better than the originating airport then continuing to the destination may be the best choice. That would be very rare though, usually a flight would divert to a much closer airport or return to the field it took off from depending on the emergency facilities available.

This happened to me while working as a flight attendant some years ago.  On a late night flight from Columbus to Cincinnati the pilots left the gear down because they saw a cockpit indication after take off that left them concerned that if they retracted the gear, they might not be able to get them back down and locked safely.  The flight was low and slow, but otherwise unremarkable.  We had a maintenance facility in Cincinnati so they wanted the plane on the ground there as opposed to returning to Columbus where there was no maintenance support.
If an airplane can land and take off with the gear extended, it's certainly air worthy for a short flight with gear extended.  Low and slow would be a given, but otherwise there shouldn't be any problem.

Gear down invokes two penalties: increased drag and reduced speed.
On modern airliners, gear down can add up to 50% more drag, so that's not an inconsequential number.
Also, the landing gear doors being open, or even partially open in the case of airliners that have some streamlining of gear in the down position, limits the maximum speed to a very low number, beyond which the doors will be torn off by the slipstream, possibly doing some nasty damage to the aircraft in the process.
That also limits the pilot's options in an emergency situation, like needing to descend quickly, or accelerate to avoid a dangerous condition, like stalling.
Finally, one has to ask... if the gear fails to retract, what else is wrong? Maybe nothing, maybe something. Could be a bad switch, could be a hydraulic leak that might also affect the flight controls, could be a piece of metal digging into the wiring harness that might later affect critical systems or start a fire. For sure, the aircraft has a problem that's out of the ordinary.
In the end, it's up to the pilot to make the call, but a failure of the gear to retract on a commercial airliner usually means getting the plane landed as soon as practical... i.e. dumping enough fuel to get down to a safe landing weight and getting clearance.
It's a lot easier to change planes or find and fix the problem, than to lose the aircraft and its passengers.

If the gears failed to retract after take off, an aircraft could carry on with its flight, but with limitations to its airspeed, cruising altitude and ATC (Air Traffic Control) would need to be informed of decreased cruising speeds and altitudes. The flight time may also be affected as increased drag from the landing gear will mean the amount of fuel may not be enough to reach the flight destination. But due the fact that most airline routes are quite far, most wouldn't be able to be completed if the gears refused to retract.

I would go further and say that the majority of airline flights could not be completed with gear extended due to excessive fuel consumption.

Yes, I think it's worth mentioning.  The principle is that if the aircraft were to take off with enough fuel to complete a flight should the gear fail to retract, then under normal circumstances that would be a significant inefficiency (since the additional weight of the extra fuel means you burn more of it).  Some very short flights would be the exceptions.

Although not a general FAA regulations, some aircraft type certifications restrict their max airspeed with gear down.  That will also restrict their service ceiling, probably so much that the original flight plan can't be flown.

It depends on circumstances if pilot have sufficient fuel, to counter increased parasite drag due to landing gear, for endurance and flight is important (due to any prospect like reputation of airlines or emergency flights etc.) than they continues their flight.
In such cases pilot must have to inform ATC for their low cruise speed and altitude.
But generally airlines do not prefer to fly with extended landing gears and used to divert to nearby airstrip. because this also restrict the airspeed and it causes delay in schedule,  but there is no regulation on this.


text:
Could some kind of impact absorbing gels be introduced into the aircraft fuselage, to minimize impact damage on passengers & cargo?
There are a lot of impact absorbing gels, one example here.
Could some kind of more advanced gel be introduced into aircraft cabins, which expand rapidly on impact (like air bags) and fill the entire cabin, thus protecting the occupants from injury or death?

I'm calling high likelyhood of that video being faked, and there is a big difference between being lightly patted by a shovel and getting smashed into the floor by 10 g of acceleration.

This post reminds me of this scene from Demolition Man (movie)

See this question; the basic answer is that human beings cannot survive the G forces in a very sudden deceleration/impact and no amount of padding will change that. The forces involved are far too high for the human body. I could also mention that there's a very high chance that video is faked, or at least misleading: you can't see what protection the person being struck really has under his clothing, so there may be much more to it than just gel.

That gel works by becoming hard and brittle with sudden impacts while being soft when slowly deformed. This requires some density, so a foam will never have this characteristic. Besides, the required stopping distance for airliner speeds is far too high, see Pondlife's comment.

Unfortunately, not to any great advantage.
An airliner travels at several hundred kilometres per hour; even when landing and flying at its slowest (which it does only for a very short time) it will still be travelling at a considerable speed.
At such speeds, any impact in a crash is likely to be characterised by two things (I've left aside fire, to concentrate on the matter of impact alone):

a very significant change in velocity (deceleration)
a release of a great deal of energy

The deceleration of an aircraft in flight that hits something will be tremendous. If you have 30 metres in which to decelerate from (say) 500 km/hr to 0, padding won't make any difference to the bodies being decelerated.
If the padding is resistant enough to prevent an object experiencing such a deceleration from simply continuing on its way and smashing through everything in its path, then the padding may as well be a block of concrete for all the softness it could offer.
On the other hand, if the padding not so hard as to smash the bodies that crash into it into pieces, then they will go straight through it and smash themselves to bits on the first harder thing they encounter.
In fact, at such decelerations, not only is there no middle way between too hard and too soft, any padding aiming for the middle ground would be simultaneously too hard (it would certainly cause catastrophic injuries to the bodies encountering it) and too soft (it wouldn't prevent them smashing into other objects).
Then, an impact of the kind you describe releases a huge amount of energy. The things involved in such impacts aren't so much as damaged as cease to exist. Everything stops being what it was. You might as well wish for padding to protect you when you're on the inside of an exploding bomb.
Perhaps you were referring to lesser impacts that would be survivable with some protection, which is reasonable. Indeed, an aircraft can readily survive turbulence that breaks the bones and heads of passengers not wearing seatbelts.
But in this case, the idea sadly fails as not very practical.

How much damage would 300 or so exploding gel pods, or airbags, do to passengers? Once again, that's a release of quite a lot of energy.
How much damage would they prevent, compared to say, just wearing seatbelts?
How much would they interfere with the subsequent evacuation?

They simply wouldn't procure any advantage, or at least, only at the cost of a much greater disadvantage.

"If you have 30 metres in which to decelerate from (say) 500 km/hr to 0" Thats not a remotely realistic scenario. The only kind of crash where that happens is an aircraft flying almost perpendicularly into terrain at a fairly large fraction of cruise speed. Almost all removely survivable crashes happen at take-off or landing, when the speed of the aircraft is more like 200km/h and the plane has much more space to stop than 30m, which isn't even the length of a 737.

At least the deceleration itself is non lethal . Going from 500km/h (139 m/s) to 0 on 30m is a mean deceleration of $\rm (0 - 139^2) / (2 \times 30) = -322 \text{m/s}^2$ or -33g. This is done on 0.26s. I believe the human body could stand these 33g eyeballs out during a quarter of second.

@DavidRicherby 500km/hr was just one example speed, and one kind of crash. I discussed the case of those lower-speed, potentially survivable accidents separately

@DanieleProcida But it's a very bad example that tells us almost nothing. It's taking a crash that's very, very far from survivable and saying, "Well, this idea wouldn't help with something close to the worst possible case, so there's no point. Oh, and by the way, it wouldn't help much with more survivable accidents." Roughly two-thirds of your answer focuses on this unreasonable case.

@DavidRicherby it might tell you nothing, but if anything is clear to someone who reads questions here regularly, there is no end to the things that that people don't realise. People aren't born knowing these things and there is no harm in spelling them out. If there's just one person for whom it is new and useful information, good.

@mins: It is, iff you can somehow spread out that deceleration evenly over that entire distance (rather than having a lot of it come in one sudden, much-larger spike), iff you're far, far better restrained than any airliner occupant, and iff you can avoid getting crushed, impaled, dismembered, etc. by pieces of collapsing and disintegrating aircraft and/or of whatever the aircraft is colliding with.


text:
Why do emergency exits over the wings have "step up and through motion" rather than having floor level exits?
My questions stems from the following paragraph from Wikipedia:

Additionally, during aircraft evacuations, it has been found that the
  majority of overwing window exit designs of Boeing 737 (NG) Next
  Generation Line along with the Airbus A320, hamper evacuation in
  comparison with traditional floor level exits due to the inherent
  "step up and through motion" required of passengers as they exit the
  aircraft, unlike the designs of older generation wide body aircraft
  such as the McDonnell Douglas DC-10 and Lockheed L1011 which are all
  floor level.

One more question I had, wouldn't it be better to have the same emergency exit procedures with respect to opening the exit door etc. on all type of commercial aircrafts?

"wouldn't it be better" are you asking for opinions? :stern_stare:

That is the second part of the question, which will largely depend on the reason of the first question. So it may be an opinion.

The McDonnell Douglas DC-10 and Lockheed L-1011 are wide body "heavy" aircraft with all door exits, no overwing window exits.  Mid fuselage doors were built into these aircraft to provide multiple points of entry and exit to speed up normal passenger boarding and deplaning, not specifically for emergency exit efficiency.  Positioning them near mid-fuselage also enables more rapid emergency evacuation as a side benefit.
Boeing 737 and Airbus 320 aircraft are traditional single-aisle designs with doors only at each end, and supplemental window exits provided over the wings.  The overwing exits are not normal passenger entry points and are sized to fit the fuselage above the wing where a door would be too large and weaken the fuselage structure too much at that location. When the FAA certifies the aircraft for emergency exit procedures, it takes into account the fact that the windows will not be able to accommodate the same number of passengers as the doors.  More recent aircraft models have improved the over wing window exits by removing one seat from that row and providing more space in the row that serves as the exit lane.
In addition to not being as large and accommodating as the main door exits, the window exits also rely on passengers to operate the exit in the first place as opposed to trained flight attendants being seated next to the door exits. When in flight attendant training, we were instructed how to open the window exits, and I can tell you they are a lot heavier that you might think, and there isn't a good place to stow them either.  But in short, the FAA knows these exits are not as efficient and may not be as reliable as the door exits.  Nevertheless the aircraft manufacturers have demonstrated the sum of all the exits are sufficient for the required evacuation time in an emergency.


text:
Why aren't the passenger seats designed as jump seats (foldable) in commercial airlines?
We know that the crew seats in an airplane are "jump seats (foldable)", which made me wonder why it isn't the same case with passenger seats.
Some advantages which I see if passenger seats are converted to the "jump seat" design:

Better access and thus easier cleaning of the aircraft
Easy entry exit by passengers
Already available tech (as in the crew jump seats)

Heavier weight, more expensive, more maintenance... You'll also notice crew jump seats are attached to a bulkhead (wall) not free standing.

Jump seats - as in crew foldable seats - are designed to give back space when they're not used. The cost is they are expensive and less comfortable. Making them standard for passenger seats is completely impractical from a cost and design perspective, and as Ron Beyer says, they are attached to a bulkhead: impossible for passenger seats except those up on the bulkhead itself.


text:
What if a passenger forcefully requested for a food which is not available on the flight?
I'd never took long flights, however curios if one day I'll fly to NewYork from India and I wish to eat my favourite dish, which may not available in kitchen of my flight, what they will do? Is there something that I've to choose from the menu only? If so, I ordered one from the menu and its not available there? However I will force air hostess to get that particular dish for me, what can be done in this situation?

I feel this should go on travel.se

Yeah this is more suitable for Travel (although I'm not totally sure it's suitable there either) - you can take food on most flights, though, within reason.

There is only so much food on the plane while it's in the air. If the dish is not available then it is not available.
Should you then throw a tantrum and the flight-attendant judges that you are a danger to themselves or other passengers or the continued flight; the pilot will then divert the flight and throw you off at the nearest available airport. After that you may be fined for the trouble you gave them.

You can request (i.e. pre-reserve) a 'special meal' (e.g. vegetarian) when you buy your ticket. But you have to do that (let them know) in advance: it's too late after the plane takes off, and too late even when you check-in.


text:
Who has authority to close a runway/airport?
In the recent runway excursion at LGA, visibility was bad, and an airport ops vehicle called the tower to inform them of the excursion and that runway 13 was closed, and then that the airport was closed.
The tower is in charge during normal operations. Who has the authority to close a runway/airport? Is this codified somewhere?
This also applies on a smaller scale, as I've heard of such things as chunks of taxiway pavement going missing.

I had the exact same question!

The guy with the rocket launcher

Generally two groups have authority to close a runway (or airport) for an incident/emergency, and if either says it's closed, it's closed:

The airport owner/operator/management.
It's their facility, so if they say it's closed, it's closed.
Specifically it's the persons authorized to issue NOTAMs for the airport who can close a runway (by issuing the NOTAM saying it's closed), but the chain of command for making this decision may vary from airport to airport.
Runways may also be closed by airport administration without issuing a NOTAM (this happens frequently at Brookhaven airport (KHWV) - "Closed Runway" X's will be put out on the crosswind runway when the banner tow operators are set up for pick-up/release on that runway). Often there's a blanket NOTAM about "banner tow ops" or similar that sort-of covers this situation (basically "Expect strange things to be happening because the banner tow people are doing...whatever it is they do".)
The control tower (if one exists).
Whether or not they have the administrative authority to "close" a runway, they certainly have the practical authority to do so by denying anyone clearance to take off/land from it or to enter it, and by issuing NOTAMs indicating that a runway is closed/unusable for some reason.

At an airport like LaGuardia where you have both an FAA Control Tower and a robust airport operations/management group (The Port Authority of New York & New Jersey) a Memorandum of Understanding (MOU) or similar agreement is likely in place to ensure that everyone knows who is authorized to do what when, but in cases like this where an aircraft has a runway excursion the course of action is pretty obvious and nobody is going to want aircraft to be moving around on the ground until the situation is under control and safety can be assured.

Note that the above is specific to shutting down temporarily for an emergency or other situation. Permanently closing a (public-use) airport or runway has some other requirements & procedures, particularly if the airport has grant obligations  for money received from the FAA (e.g. under the Airport Improvement Program).

As ATC, I was specifically taught that I do not have legal authority to consider a runway closed. Of course as you say it's certainly in my prerogative to withhold takeoff or landing clearance even if the runway is "open" on paper.

In addition to the categories listed above, pilots have the authority to close a runway. A braking action nil report will automatically close that runway until the airport operator is satisfied that the condition no longer exists.
Winter Ops AC Change

I'm not sure I consider that the authority of the pilots. Technically they can also close the airport by skidding off the runway. And anyone could close it with a threat. But they aren't the ones actually making the move to close it.

This is kind of a gray area, but there is a procedure...
Theoretically, the way a runway is closed is that the airport or airfield operator notifies, in writing, the FAA thirty days ahead of time that a publicly-accessible runway will be closed. The FAA then issues a NOTAM about the closure and the airport puts big X's on the runway at either end. The runway is then closed.
In the event of accident, you obviously cannot "close" a runway this way. The best you can do is warn pilots off it. Since there is no way to "close" a runway on a short-term basis, what happens is that they "close" the entire airport, which is what happened at La Guardia. There is no NOTAM or forewarning during the initial response, so small aircraft can potentially still arrive and they have to be warned off.
Unfortunately, a lot of police and firemen do not understand this, so they try to "close" a runway just by ordering the tower to close it. Often, they do not even do this; they just rush onto the tarmac without even waiting to get permission or calling anyone. Obviously this creates incredibly dangerous situations. The tower (if there is one) reacts to this irregular action by notifying ATC and making constant do-not-land-here warnings on the common channel(s). If there is no tower, hopefully there are people on the ground with radios who do the same thing.
Just as an example of how dangerous this can become: once I was at an airfield with no tower and an aircraft landed short in the trees, getting hung up in some branches. A bunch of state police cars and fire engines literally drove down the runway to get to him like it was a road or something. The danger here is that many smaller aircraft or ultralights (etc) may not have (working) radios or may be on the wrong frequency so they have no idea what is happening. They could have just landed on one of the cop cars and blown up killing everybody. After it happened we called the police and told them how to drive on side of the airfield (not down the runway !!!) and provided them with emergency route maps, but at a certain level it is whistling in the dark, because most emergency personnel do not read these materials.

However, large airports are not allowed to operate without having available a full emergency response service. If they are all busy attending to a crashed aircraft, the airport legally cannot authorise another aircraft movement. So whilst technically the rescue service may not have the authority to close it down (I'm not certain of the formalities), in reality they can tell the tower that the airport is closed, like they did at LGA this week.

I've had the "pleasure" of seeing a few airport emergency responses, and at no time did the fire crew "rush onto the tarmac without even waiting to get permission or calling anyone" - EVERY move by the fire crew on movement areas was coordinated with the tower & the rescue equipment requested & was cleared for each move they wanted to make. Things may be different at Uncontrolled Podunk Municipal with volunteer firefighters responding, but at a towered field with dedicated ARFF teams (such as LGA) it is nowhere near as chaotic as you make it out to be.

(for that matter even if the local fire department goes barreling onto the runway at Uncontrolled Podunk Municipal surely pilots are making a proper overhead pass before entering the pattern as recommended in the AIM, and keeping a careful eye on the field on downwind/base/final so they'd notice a big ol' honkin fire engine on the runway (or perhaps the thing that motivated them to show up to begin with). We're not all as oblivious as a United States Senator – at least I hope not!)

"The tower (if there is one) reacts to this irregular action by notifying ATC" the tower notifies ATC? What is the tower if not ATC?

@raptortech97 By "ATC" in this context I am referring to non-local control such as ARTCCs and TRACONS.

@voretaq7 Yeah, I took his answer to be more referring to Podunk Municipal than, say, LGA. I'm guessing the emergency crews near the airport I usually fly out of would have no idea that it would be advisable to contact someone before driving onto the runway. Of course, I agree that pilots should look out their window and notice the pretty red vehicles on the runway.

@reirab Why do you guess that? Fire crews dealing with, for example, chemical incidents are perfectly capable of liaising with factory management so they know what's safe. Why aren't firecrews dealing with aviation incidents capable of liaising with aviation management so they know what's safe?

The danger is not that the pilot would not see a fire truck on the runway, the danger is that the truck or police car would drive onto the runway (or cross taxiway) as an aircraft was landing.


text:
What is the record length of time for single-occupant flight?
What is the longest flight time for a single pilot alone in an aircraft?

I found a number of relevant results by searching "longest solo flight" in Google.

Relevant Meta discussion

@greg me too (but only after relalizing i should use the word "solo") and I don't know which, if any, is correct.

Glider pilots can go for aaaaaggges, are they within the scope of your question?

@ben yeah! They are :)

U-2 pilots do long flights too. 8 hours is mentioned on Wikipedia.

Aviation records can be researched at the Fédération Aéronautique Internationale (FAI) web site.

What is the longest flight time for a single pilot alone in an aircraft?

13 days if a balloon counts as an aircraft.
Balloon
Steve Fossett set a record in 2002

In 2002, he became the first person to fly around the world alone, nonstop in any kind of aircraft. He launched the 10-story high balloon Spirit of Freedom from Northam, Western Australia on June 19, 2002 and returned to Australia on July 3, 2002, subsequently landing in Queensland. Duration and distance of this solo balloon flight was 13 days, 8 hours, 33 minutes (14 days 19 hours 50 minutes to landing), 20,626.48 statute miles (33,195.10 km).

Other types of aircraft
The following information was volunteered in comments by Scary Spice and Peter Kämpf.
Glider
Charles Atger, stayed aloft for 56.25 hours, solo.
Powered airplane
Charles Lindbergh was all by himself for 33.5 hours.
Spacecraft
Ron Evans, Apollo 17 Command Module Pilot, was alone for 79 hours, 49 minutes.

What was the "powered airplane" that was used to set the record?

Wasn't it the Spirit of St. Andrew?  Or maybe St Peter...

The Fédération Aéronautique Internationale (FAI) does no longer accept new records for endurance flights of airplanes and gliders for safety reasons. They used to have such a category until at least the mid 1930s.
The longest powered, unrefueled, solo flight I was able to find is the circumnavigation of the Earth by Steve Fossett in the Virgin Atlantic GlobalFlyer. After taking of on February 8, 2006, at 12:22 UTC he flew for 76 hours and 45 minutes and travelled an official distance of 41,467 km.

Wow!  Do you know if he used AutoPilot?  Seems that would make it a bit easier...